Other domestic media have reported that the figure could be as much as 700 billion yen, while sources have previously told Reuters it could be more than 500 billion yen (3.5 billion pounds).

A Toshiba spokesman said that nothing concrete has been decided yet. It plans to announce the size of the writedown on Feb. 14 with its third-quarter results.

Toshiba is rushing to raise funds by the end of the financial year in March as a massive charge could wipe out shareholders equity that has shrunk to just $3 billion in thewake of a 2015 accounting scandal.

The conglomerate's board will meet on Friday to approve plans to make its core chip business a separate company and hopes to raise more than 200 billion yen by selling a 20 percent stake in it, a person with direct knowledge of the matter said.

(Reporting by Junko Fujita; Editing by Edwina Gibbs)